Ski



FIG. 1 is a front perspective view of a ski showing our new design;

FIG. 2 is a bottom perspective view thereof;

FIG. 3 is a top plan view thereof;

FIG. 4 is a bottom plan view thereof;

FIG. 5 is a side plan view thereof;

FIG. 6 is a front elevational view thereof; and,

FIG. 7 is a rear elevational view thereof; any broken line illustration forms no part of the claimed design. 

The ornamental design for a ski, as shown. 